1. Field of the Invention
The present invention relates to sound-vibration generating devices to be incorporated into portable communications devices such as portable telephones and pagers, or small devices such as wristwatches and toys.
2. Description of the Related Art
Conventional portable telephones have incorporated therein a sound generator (ringer) for notifying the user of incoming calls with sound, and a vibration generator for notifying the user of incoming calls by vibrating the body of the telephone. One of the two generators is selectively usable according to the situation.
However, a sufficient space is not available in small devices such as portable telephones for accommodating both the sound generator and the vibration generator, and the provision of these two generators entails the problem of making the device larger.
Accordingly, the present inventor has proposed a compact sound-vibration generating device having the functions of both the sound generator and the vibration generator as shown in FIGS. 13 and 14 (JP-A No. 14194/1998).
The sound-vibration generating device includes two vibration systems housed in a resin casing 110. The casing 110 includes a lower case 110a for supporting a first vibration system, and an upper case 110b for supporting a second vibration system. The upper case 110b has a sound release aperture 111 formed in its central portion.
The first vibration system includes a first diaphragm 112 having a plurality of swirling slits, and a first vibrator 116 having a permanent magnet 113. The first vibrator 116 is attached by adhesion to the inner peripheral portion of the first diaphragm 112, the outer peripheral portion of which is attached to the lower case 110a by adhesion. The first vibration system can therefore be vibrated up and down relative to the lower case 110a. The first vibrator 116 includes an upper yoke 114 and a lower yoke 115 which are arranged respectively on the upper and lower sides of the permanent magnet 113, whereby a magnetic circuit is provided. The magnet 113 is magnetized such that the upper side thereof provides an N pole, with the lower side thereof serving as an S pole. The upper yoke 114 is in the form of a ring having an inner periphery formed by a vertical wall, while the lower yoke 115 is in the form of a disk having a central protrusion. A magnetic gap 121 is formed between the vertical wall of the upper yoke 114 and the central protrusion of the lower yoke 115 for making a second vibrator 117 movable up and down.
On the other hand, the second vibration system includes a second diaphragm 122, and the second vibrator 117 which has a coil 118. The second diaphragm 122 has an inner peripheral portion having the second vibrator 117 attached thereto by adhesion and an outer peripheral portion attached to the upper case 110b by adhesion, whereby the second vibration system is made vibratable vertically relative to the upper case 110b. The coil 118 of the second vibrator 117 is supported by a hollow cylindrical bobbin 119 on the rear side of the second diaphragm 122. The coil 118 and the bobbin 119 are arranged such as to be movable in the magnetic gap 121 of the first vibrator 116.
The second vibration system has a natural frequency (for example, of about 2 kHz) in the audible range, while the first vibration system has a lower natural frequency (for example, of about 100 Hz) than the second vibration system. Accordingly, the second vibration system can be resonated to produce sound by connecting a drive circuit (not shown) to a pair of free ends 123, 123 of the coil 118 and feeding to the coil 118 a drive signal having the natural frequency of the second vibration system. On the other hand, the first vibration system can be resonated to produce a vibration perceivable by the human body by feeding to the coil 118 a drive signal having the natural frequency of the first vibration system.
A study is under way on a method of mounting the sound-vibration generating device on a printed wiring board by inserting a pair of terminal pins through an end portion of the casing 110 axially of the casing, attaching the pins to the end portion, connecting the pair of free ends of the coil 118 to the upper ends of the respective terminal pins, inserting the lower ends of the terminal pins through holes in the wiring board to position the sound-vibration generating device in place, and soldering the pin lower ends to the rear surface of the wiring board for electrical connection, i.e., a mounting method by dipping.
However, the mounting method by dipping permits the lower ends of the terminal pins and the solder joints to project from the rear surface of the printed wiring board, resulting in an increased thickness for the assembly of printed wiring board and an increased size for the device, such as a portable telephone, in which the generating device is to be incorporated.
Moreover, dipping involves the necessity of performing the step of solder reflow separately from the assembly step of installing the sound-vibration generating device on the printed wiring board, resulting in an increased manufacturing cost.
Accordingly, a first object of the present invention is to provide a sound-vibration generating device which is adapted for surface mounting to thereby overcome all the foregoing problems.
In the case where the conventional sound-vibration generating device is to be incorporated into small devices such as portable telephones, there is a need to fix the rear surface of the casing 110 to the surface of a printed wiring board or the like, whereas because the first vibration system is especially great in mass of vibration to produce a great vibrating force through resonance, sufficient rigidity is required of the casing 110, especially of the lower case 110a serving as the support portion. Furthermore, the adhesive joint between the outer peripheral portion of the first diaphragm 112 and the lower case 110a which is subjected directly to the force of vibration requires a sufficient adhesion strength to receive the force of vibration.
The conventional sound-vibration generating device nevertheless suffers from the problem that an effective construction is not always utilized for providing sufficient rigidity to the lower case 110a and imparting a satisfactory adhesion strength to the adhesive joint between the outer peripheral portion of the first diaphragm 112 and the lower case 110a. 
Accordingly, a second object of the present invention is to provide a sound-vibration generating device the body of which is supportable with sufficient rigidity and which has satisfactory strength against vibrating force produced by vibration.
The diaphragm 112 of the first vibration system has a spring structure provided with a plurality of swirling slits to produce a great amplitude, so that when subjected to an impact, for example, after falling, the first vibration system becomes excessively displaced, not only permitting the excessive displacement to cause damage to the diaphragm itself but also allowing the upper yoke 114 or lower yoke 115 to come into direct contact with the diaphragm 122 of the second vibration system to possibly cause damage also to the second diaphragm 122. Because the diaphragms 112, 122 are relatively low in strength, there arises the problem that the sound-vibration generating device fails to operate normally.
Accordingly, a third object of the present invention is to provide a sound-vibration generating device in which the diaphragm or like component is unlikely to be damaged even if subjected to an impact.
The present invention provides a first sound-vibration generating device which includes as arranged in a main body case 10 a sound generating unit 9 for producing sound toward the outside of the main body case 10, and a vibration generating unit 6 for vibrating the main body case 10.
The main body case 10 has attached to a bottom portion thereof a bottom plate 12 to be soldered to a land on a printed wiring board, the main body case 10 being provided at an end portion thereof with a pair of connecting terminals 13, 14 for receiving a drive signal for driving the sound generating unit 9 and/or the vibration generating unit 6, the connecting terminals 13, 14 being provided at lower ends thereof with joint portions 13a, 14a to be soldered to respective lands on the printed wiring board, a rear surface of the bottom plate 12 and rear faces of the joint portions 13a, 14a of the terminals 13, 14 being positioned on the same plane or approximately the same plane.
Stated more specifically, the vibration generating unit 6 includes a magnet assembly attached to the main body case 10 by a first diaphragm 1, and the sound generating unit 9 includes a coil 7 attached to the main body case 10 by a second diaphragm 8, the magnet assembly having a magnetic gap for accommodating therein the coil 7 of the sound generating unit 9, the coil 7 having a pair of free ends 7b, 7b connected to the pair of connecting terminals 13, 14.
The surface of the printed wiring board 21 on which the sound-vibration generating device of the present invention is to be installed has a land for joining the base plate 12 thereto by soldering, and lands for joining the joint portions 13a, 14b of the pair of terminals 13, 14 thereto by soldering. The lands are covered with a solder paste applied thereto. The sound-vibration generating device of the invention is placed in position on the surface of the printed wiring board 21.
Because the rear surface of the bottom plate 12 is positioned on the same plane or approximately the same plane as the rear faces of the joint portions 13a, 14a of the pair of connecting terminals 13, 14, these joint portions are brought into intimate contact with the lands on the wiring board 21. In this state, the board is subjected to a reflow treatment, whereby the bottom plate 12 and the pair of terminals 13, 14 are soldered to the respective lands on the board.
The bottom plate 12 is soldered to the land on the wiring board 21 in this way, whereby the sound-vibration generating device is firmly secured to the printed wiring board, and the pair of connecting terminals 13, 14 are soldered to the corresponding lands on the board 21 to thereby connect the device to the board electrically.
The first diaphragm 1 in the specific construction is in the form of a disk and secured to the main body case 10 with an outer peripheral portion 1e thereof held between the main body case 10 and the bottom plate 12.
This construction permits the bottom plate 12 to serve also as the member for securing the first diaphragm 1 to the main body case 10, whereby the number of components can be reduced.
The main body case 10 is in the form of a hollow cylinder, and the pair of connecting terminals 13, 14 extend through a holder 10i provided on an outer peripheral portion of the main body case 10 and are attached to the main body case 10.
Because the main body case 10 is cylindrical in this construction, a dead space is invariably formed on the printed wiring board 21, whereas the holder 10i and the pair of terminals 13, 14 are arranged in the dead space. This assures effective use of the dead space, further permitting use of a board of smaller size.
Each of the connecting terminals 13, 14 includes a striplike terminal body 13b extending in the direction of extension of the terminal through the holder 10i and provided on opposite sides thereof with wedge portions 13c, 13d projecting in directions orthogonal to the direction of extension.
With this specific construction, the terminals 13, 14 are inserted through the holder 10i for assembly, permitting the wedge portions 13c, 13d to bite in the holder 10i to produce a wedge effect, with the result that the terminals 13, 14 can be reliably held to the holder 10i without the ready likelihood of shifting.
Each of the connecting terminals 13, 14 is provided at an upper end portion thereof with a winding portion 13e for connecting the free end 7b of the coil 7 thereto, whereby the free ends 7b, 7b of the coil 7 can be easily and reliably connected to the respective terminals 13, 14, which themselves are effectively prevented from slipping off.
The rear faces of the joint portions 13a, 14a of the connecting terminals 13, 14 slightly project toward the printed wiring board beyond the rear surface of the bottom plate 12. Accordingly, when a reflow treatment is conducted with the sound-vibration generating device placed on the printed wiring board and with the bottom plate 12 and the joint portions 13a, 14a of the pair of terminals 13, 14 pressed against respective solder paste layers for surface mounting, the joint portions 13a, 14a of the terminals 13, 14 are joined to the lands on the wiring bond under high pressure to realize reliable electrical connection.
Because the first sound-vibration generating device of the present invention can be mounted on the surface of the printed wiring board as described above, the portable telephone or like device in which the generating device is to be incorporated can be made more compact. Moreover, there is no need to separate the solder reflow step from the step of placing the sound-vibration generating device on the printed wiring board to result in a manufacturing cost reduction.
The present invention provides a second sound-vibration generating device having a casing including a main body case 10 in the form of a hollow cylinder and a bottom plate 12 in the form of a disk and attached to an opening portion of the main body case 10, the casing having arranged therein a sound generating unit 9 for producing sound toward the outside of the casing and a vibration generating unit 6 for vibrating the casing.
A diaphragm 1 constituting the vibration generating unit 6 is secured to the main body case 10 with an outer peripheral portion 1e thereof held between the main body case 10 and the bottom plate 12.
The bottom plate 12 is made from a metal plate and includes a circular traylike body and a flange 12i projecting from an outer periphery of the body radially thereof, the outer peripheral portion 1e of the diaphragm 1 being held between the flange 12i of the bottom plate 12 and a face of the main body case 10 opposed to the flange.
With the sound-vibration generating device of the present invention, the bottom plate 12 includes a traylike body and a flange 12i projecting therefrom and is so shaped in section as to have high rigidity, so that the device body including the main body case 10, sound generating unit 9 and vibration generating unit 6 can be supported with sufficient rigidity by the bottom plate 12 as secured to the surface of the printed wiring board.
Furthermore, the flange 12i formed on the bottom plate 12 affords an increased area of contact for holding the diaphragm 1 between the bottom plate and the main body case 10, with the result that the diaphragm 1 can be firmly held between the flange 12i and the face of the case 10 opposed thereto. This affords a sufficient strength to receive a great force of vibration that would be produced by the generation of vibration.
Stated more specifically, the traylike body of the bottom plate 12 comprises a disk portion 12g, and a cylindrical portion 12h projecting from an outer peripheral edge of the disk portion axially thereof, the flange 12i projecting from an axial end of the cylindrical portion 12h. 
An outer peripheral end face 12a of the flange 12i is fitted in an inner periphery 10c of the main body case 10 in pressing contact therewith and adhered thereto, whereby the bottom plate 12 is secured to the main body case 10.
Consequently, the bottom plate 12, even if having a small thickness, can be secured to the main body case 10 with the highest possible strength.
An annular clearance 12d is formed between an outer periphery 12c of the cylindrical portion 12h of the bottom plate 12 and an inner periphery 10e of the main body case 10 and filled with an adhesive.
This specific construction enables the adhesive to secure the bottom plate 12 to the main body case with a still higher bond strength.
Further according to the specific construction of the invention, the bottom plate 12 has a material and a shape so as to be joined by soldering to a land on a printed wiring board, the main body case 10 being provided at an end portion thereof with a pair of connecting terminals 13, 14 for receiving a drive signal for driving the sound generating unit 9 and/or the vibration generating unit 6, the connecting terminals 13, 14 being provided at lower ends thereof with joint portions 13a, 14a to be soldered to respective lands on the printed wiring board, a rear surface of the bottom plate 12 and rear faces of the joint portions 13a, 14a of the terminals 13, 14 being positioned on the same plane or approximately the same plane.
When the sound-vibration generating device having this specific construction is to be mounted on the surface of the printed wiring board, a land is formed on the wiring board for joining the base plate 12 thereto by soldering, with lands also formed thereon for joining the pair of terminals 13, 14 thereto by soldering. The lands are covered with a solder paste applied thereto.
Because the rear surface of the bottom plate 12 is positioned on the same plane or approximately the same plane as the rear faces of the joint portions 13a, 14a of the pair of connecting terminals 13, 14, these rear faces are brought into intimate contact with the lands on the wiring board 21. In this state, the board is subjected to a reflow treatment, whereby the bottom plate 12 and the pair of terminals 13, 14 are soldered to the respective lands on the board.
The bottom plate 12 is soldered to the land on the wiring board 21 in this way, whereby the sound-vibration generating device is firmly secured to the printed wiring board, and the pair of connecting terminals 13, 14 are soldered to the corresponding lands on the board 21 to thereby connect the device to the board electrically.
According to the second sound-vibration generating device of the present invention, the sectional shape of the bottom plate including a traylike body and a flange projecting therefrom enables the bottom plate to support the device body with sufficient rigidity, also affording a sufficient strength against the force of vibration produced by the generation of vibration as described above.
The present invention provides a third sound-vibration generating device including as arranged in a casing a sound generating unit 9 for producing sound toward the outside of the casing, and a vibration generating unit 6 for vibrating the casing, wherein the casing is provided with a stopper for limiting the shift of the vibration generating unit 6.
Stated more specifically, the vibration generating unit 6 includes a magnet assembly attached to a main body case 10 by a first diaphragm 1, and the sound generating unit 9 includes a coil 7 attached to the main body case 10 by a second diaphragm 8, the magnet assembly having a magnetic gap for accommodating therein the coil 7 of the sound generating unit 9.
When the vibration generating unit 6 is about to be shifted greatly by an impact acting on the sound-vibration generating device of the invention, the unit 6 comes into contact with the stopper in the course of shifting to limit the shift.
This not only eliminates the likelihood that the first diaphragm 1 itself of the vibration generating unit 1 will be damaged by an excessive shift but also prevents the magnet assembly from colliding directly with the second diaphragm 8, whereby the second diaphragm 8 is also protected against damage. Further because the end face 7c of the coil 7 is prevented from colliding with the bottom surface 2b of the lower yoke 2, the coil 7 is unlikely to become damaged.
Stated more specifically, the stopper includes an upper stopper 10h and a lower stopper 12f with which the magnet assembly of the vibration generating unit 6 comes into contact. This assures safety with respect to either direction of shifting.
The upper stopper 10h is formed on an inner peripheral surface of the main body case 10, and the lower stopper 12f is formed on a surface of a bottom plate 12. This specific construction will not add to the number of components because the two stoppers 10h, 12f can be provided integrally with the respective main body case 10 and bottom plate 12.
Even when the third sound-vibration generating device of the invention is subjected to an impact, for example, upon falling, the excessive shifting of the vibration generating unit 6 is limited to obviate the likelihood of the diaphragm 1 or 8, the coil 7 or like component becoming damaged as described above.